dB Limiter for IEM?

[Silvershads]

Hi Folks

 

I've just bought a pair of T1 triple driver custom moulded IEMs from ACS in Banbury and am waiting for them to arrive. Terrified I'm not going to like them but, at the price I'm paying for them, I guess I'm going to have to learn to like 'em! :)

 

The question I wanted to ask revolved around these IEMs. Anything that isolates by as much as 26dB is going to result in my not hearing very much outside of what's being pumped to me by the sound engineer and I'm forever concerned - anything like a mistake from said engineer, or sudden loud feedback through the monitor system, etc. could result in hearing damage for me. I wanted to know if there is such a thing as a decibel limiter I can place in-line with my IEMs so that, no matter what happens out on the desk, FOH - anywhere, I'm protected should there be a sudden loud noise which potentially could be transmitted to me?

 

Any suggestions/help with this would be incredible. Many thanks in anticipation.

 

Cheers

Chris

[paulears]

Lots of people do use an in line brickwall type limiter for safety, but I must admit that I've never found it necessary as the limiter in the transmitter is enough. What seems to happen is that the top limit has to be set to keep the transmitter from overdeviating, and as overdeviation produces such a nasty sound, stopping it happening is a crucial element of the transmission chain through to the receiver. All I'd do is set the receiver volume fairly low, then experiment with pushing the audio level to the transmitter. I use Sennheisers quite often, and have a Trantec system of my own, that I use on comms, and I've never had a problem, even when somebody opens a mic standing next to a monitor going full tilt - I've never had that need to wrench them out.

 

One tip. If you have had custom ear moulds made, keep them scrupulously clean. I must admit I wasn't very good at this, and I have a recurring infection that keeps coming back in my right ear that makes wearing the proper mould very painful. Antibiotic ear drops seem to work, but it's something I didn't think much about before, leaving them lying around on the desk, and stuffing them in a pocket.

[Silvershads]

Hi Paul

 

Many thanks for the quick return post. Very interesting point re the limiting on the transmitter. I'm using a Shure PMS200 system (at least I think it's the 200). The belt unit has a volume/on/off dial on it, so I could turn the volume to the ACS earphones down and get the desk guru to send me a higher overall volume level. It there is a limiter on the transmitter I'm going to be very relieved. I really am worried about the potential for ear damage and I will do anything I need to, to stop that from happening.

 

Off I go to have a look at the Shure website to see what, if anything, they say about the PMS 200 unit.

 

Regards

Chris

 

A concurrent post has been automatically merged from this point on.

 

OH! And thanks for the tip re cleaning. If you know of a product that won't react badly with the silicon the IEMs are made of, I'd appreciate hearing about it.

 

Cheers

Chris

[Gareth Owen]

I too have had infections from custom moulds. These days I keep a few antiseptic wipes in the pouch with my IEMs to give them a once over before use.

 

Am I right in thinking some systems have limiters in the recievers, some in the transmitters? I have an idea that Trantec S5000 IEMs have the limiter in the TX but that the Shure PSM700 stuff has the limiter in the receiver?

 

In these days of digital desks you can also ask the monitor engineer to put a limiter over your mix output from the console. In analouge land a simple brickwall limiter inserted across the output could be beneficial too.

[Silvershads]

Hi Gareth

 

In these days of digital desks you can also ask the monitor engineer to put a limiter over your mix output from the console. In analouge land a simple brickwall limiter inserted across the output could be beneficial too.

Can you explain to this dumbo what a "brickwall limiter" is and how to set one up on an analog desk? We're using a Yamaha MG24/14. Is this something we set up on desk or is it something we have to make up and insert into a cable?

 

I too have had infections from custom moulds. These days I keep a few antiseptic wipes in the pouch with my IEMs to give them a once over before use.

Gotcha! I will get some wipes and stick 'em in the pouch with the IEMs. Thanks for that.

 

Cheers

Chris

[Kevin Ross]

A brick wall limiter is either a unit specifically designed unit or a compressor with the ratio turned up to infinity:1 and a 0ms attack time (Yes pedants I know that technically they are not the same thing but for the purposes of this demonstration lets assume they are.)

 

 

 

Anyway basically it stops the level going beyond a certain point no matter how hard you push the level. They are a good safety net to have but don’t make a habit of hitting it too often.

 

 

 

Some sound better than others but most at the lower end will colour the sound in some way. A good cheep unit like the cloud CX335 can be found on eBay for cheep. I have 2 of them for other limiting duties and they sound good even when being rammed into the limiter

 

 

 

For your desk which I think does not have AUX inserts you would have to come out for the AUX out on the desk into the limiter then out of the limiter into the transmitter

[Peter F]

Off I go to have a look at the Shure website to see what, if anything, they say about the PMS 200 unit.

 

Shure PSM 200 has a limiter built into the receiver.

 

As does the PSM 700 as Gareth thought (and the 400 & 600 models also)

 

You can switch off the limiter on the 400, 600 & 700 series.

You cannot on the PSM 200 model.

 

Cheers,

 

Peter

[AndyL]

Am I right in thinking some systems have limiters in the recievers, some in the transmitters? I have an idea that Trantec S5000 IEMs have the limiter in the TX but that the Shure PSM700 stuff has the limiter in the receiver?

 

All IEMs (and radio mics) should incorporate a peak deviation limiter to ensure that the transmission stays within channel limits, I'm sure this is the case with all reputable brands. On its own that probably isn't something you would want to rely on to protect your ears. Plus any limiter at the transmitter will not protect you from peaks of noise that did not originate from the input to that transmitter. The level of noise that you can get through your moulds if the squelch opens on a blank frequency is going to be very loud; e.g. if the TX gets powered down whilst you are doing your walk around listening to the noise floor with the pack at max volume trying to find that elusive dead spot that the singer keeps complaining about.... So to be effective in all circumstances you really do need the volume limiter to be at the RX end.

 

All Sennheiser IEM's have incorporated some form of switchable volume limiter on the receiver pack. On the original 3000 series and Evolution 'G1' it simply took the form of an attenuator which 'limited' the maximum possible volume you could get out of the receiver without any dynamics element to it. Crude yes, but it did get around any arguments about the ballistics of the limiter affecting the sound! On Evolution 300 IEM G2 and all other models since there is a more conventional, proper, switchable, limiter in the receivers which is in by default on the factory preset. Guess what's the first thing most monitor engineers do / ask for when you give them the packs.... 'can you make sure all the limiters are off'.

 

Canford audio do in line volume limiters for headphones. Presumably they could be used on IEM moulds given the impedance and sensititvity figures to calculate a limit value from.

[TimmyP1955]

http://cgi.ebay.com/Rane-MM42-IEM-In-Ear-M...93%3A1|294%3A50

 

if that does not work, try http://cgi.ebay.com/Rane-MM42-IEM-In-Ear-M...emZ270415024038

[Silvershads]

Thanks to all for the helpful responses and apologies for the delay getting this post back into the system.

 

I ended up with ACS IEMs and DPA head mic. The Shure PSM200 transmitter does indeed have a limiter built in both to the transmixer and the headphone receiver pack. As some wise person said, they are not switchable but are on all the time. What a relief to know I'm not going to be deafened suddenly, although we had some feedback on Sunday evening and it was LOUD in my custom moulded earpieces! <grumble>

 

I have some more stupid questions to ask about mix and stuff for the IEMs but will start another thread for that.

 

Thanks again!

Chris